Channel catfish virus (CCV) disease is a highly virulent and communicable disease of fry and fingerling channel catfish (Ictalurus punctates Raf. ) which was discovered by Fijan in 1968. (Bull. Off. Int. Epizoot., 69: 1167-68, 1968). Presently, the geographical range of the disease extends from West Virginia to California and Alabama to Nebraska. Since its isolation, the number of states in which epizootics have occurred have increased from four to at least eleven states and one foreign country. Continued extension of the range of the disease is a real possibility since survivors of an epizootic may become asymptomatic carriers from whom virus cannot be isolated.
Mortality rates may range from less than 50% to 100% in affected tests. The highest percentage mortality occurs during the first summer of life when the fish weigh less than 10 g and are less than 10 cm in length. As the fish become larger, the mortality may be reduced and the disease prolonged; but epizootics have occurred in ponds where over 99% of 50,000 5-6 cm fingerlings died in less than one week. (Plumb, J. A. The Catfish Farmer and World Aqua. News, 6 (3): 40-42 (1974).
Considering the increasing importance of the channel catfish as a food source, the desirability of obtaining a vaccine for CCV to prevent the economic loss in private and federal hatcheries is evident. CCV is considered to be one of the eight most serious communicable diseases of fish in North America. The disease is probably more prevalent than indicated in the literature since commercial farms are reluctant to report outbreaks due to a fear of suffering business losses as regular and prospective customers might fear introduction of the disease into their facilities.
The culture of channel catfish as a protein source for human and animal consumption is a highly profitable, international business. A vaccine which would protect against the highly devastating effects of CCV disease is very desirable for a number of reasons. First, there is no known treatment of the disease--diseased fish and broodstock are necessarily destroyed at great cost and loss of time. Second, control of the disease is practiced through avoidance, quarantine and disinfection. However, this approach is costly and of limited values since asymptomatic carries of the disease may re-introduce it into a population.